A Case of Diverticular Perforation in a Young Patient with Rheumatoid Arthritis on Methotrexate.

Background. Disease-modifying antirheumatic drugs (DMARDs), such as methotrexate (MTX), are associated with gastrointestinal toxicity. MTX inhibits dihydrofolate reductase, but it is unclear if polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene predict toxicity. Case. We describe a 33-year-old male with polyarticular rheumatoid arthritis who developed sigmoid diverticular perforation while receiving methotrexate, folic acid, prednisone, and naproxen. He tested heterozygous for the C677T allele MTHFR gene. Discussion. Rheumatoid arthritis and its treatments are associated with increased risk of gastrointestinal disease. In one study, perforation was highest among individuals with concomitant exposure to NSAIDs, nonbiologic DMARDs, and glucocorticoids. Multiple mutations of the MTHFR gene have been identified, but their association with MTX toxicity is unclear. This case adds to a growing body of literature that could help inform the treatment of others in the future.